Removable push electrical fitting for electrical metallic tubing or emt

ABSTRACT

An electrical fitting having a gripping device with a plurality of gripping tabs forming a helix or spiral. The electrical fitting permits electrical metallic tubing or EMT to be quickly attached to and removed from the electrical fitting without disassembling the fitting or cutting the tubing. A body with a locking end having a plurality of griping tabs receives an end of the tubing pushed into the fitting. The gripping tabs securely hold the tubing preventing loosening or removal. The helix or spiral formation of the griping tabs permits easy removal of the tubing by rotating the tubing counter-clockwise.

FIELD OF THE INVENTION

The present invention relates in general to an electrical fitting, andmore particularly to a push fitting, connector, or coupler for attachingelectrical metallic tubing or EMT that is easily removable withoutdisassembly of the fitting.

BACKGROUND OF THE INVENTION

There are many electrical fittings and connectors that are used inconstruction. Pipes or tubing have been used to contain conductors orelectrical wires. The pipes or tubing containing electrical wires areconnected to electrical boxes through electrical fittings, such asconnectors or couplers. Often electrical metallic tubing is used, muchlike pipe, to act as a conduit through which electrical wires orconductors are run. Due to the large number of connections typicallymade with electrical wires in construction, there is a need for an easyto use fitting, connector, or coupler for connecting tubing to anelectrical box or coupling two tubes together. Accordingly there aremany devices that are used to connect or couple tubing, with eachconnector or coupler having some particular advantage.

One such connector is disclosed in U.S. Pat. No. 3,312,483 entitled“Pipe Connector” and issuing to Ledbetter et al on Apr. 4, 1960. Thereindisclosed is a pipe connector using a ring provided with a series ofradially and axially extending slits which define a plurality of tabs.The tabs swing inwardly, thus biting into the plastic pipe.

Another pipe fitting is disclosed in U.S. Pat. No. 4,073,514 entitled“Combination Pipe Fitting and Retainer Ring” issuing to Pate on Feb. 14,1978. Therein disclosed is a retainer ring having tabs. The retainerring is held into the fitting by a groove or recess and an anchor tab.

Another fitting is disclosed in U.S. Pat. No. 6,670,553 entitled “SnapEngagement Electrical Fitting for EMT” issuing to Gretz on Dec. 30,2003. Therein disclosed is a fitting that provides a snap-in engagementwith electrical metallic tubing. A plurality of locking tangs are lancedlongitudinally and bent inwardly. Arcuate edges on the leading ends ofthe locking tangs dig into the outer surface of the electrical metallictubing thereby holding it fast to the trailing end of the connector.

Yet another fitting is disclosed in U.S. Pat. No. 6,913,298 entitled“Mechanical Pipe Coupling Derived from a Standard Fitting”, and issuingto Snyder, Sr. et al on Jul. 5, 2005. Therein disclosed is a retainerhaving a plurality of radial teeth angularly oriented to engage a pipeand prevent its removal from the coupling.

While all of these fittings or connectors have performed well inpermitting the inserting of a pipe or tubing that is relatively securelyheld, they have not permitted easy removal of the pipe or tubing shouldit be desired to uncouple the pipe or tubing. Generally, once theseconnectors have been assembled, if a change or modification is required,the pipe or tubing cannot be removed without cutting the tubing ordisassembling the fitting. This is often a time consuming and difficultprocess which makes any subsequent modification of the configuration ofthe pipe or tubing difficult.

Therefore, there is the need for a simple, easy to use electricalfitting, connector, or coupler in which electrical metallic tubing maybe simply pushed into the connector or coupler with the electricalmetallic tubing being securely held and yet that permits easilyremovable of the electrical metallic tubing from the fitting, connector,or coupler when desired.

SUMMARY OF THE INVENTION

The present invention permits easy assembly of electrical metallictubing used for running wire or conductors for making electricalconnections that can be assembled by simply pushing the electricalmetallic tubing into the fitting, connector, or coupler and yet that iseasily removable without disassembling the fitting, connector, orcoupler. The present invention is an electrical fitting comprising aconnector body having a gripping device securely held therein. Thegripping device has a plurality of gripping tabs that are arranged alonga helix or spiral. The gripping tabs are of equal lengths and areequally spaced along a circle and originate from a ramp. The grippingtabs are positioned along the ramp at a different position relative tothe longitudinal axis of the connector body of the fitting, connector,or coupler. The gripping tabs flex away from an opening in the fittingpermitting the electrical matallic tubing to be pushed into the fittingthrough the opening. The angled gripping tabs prevent the electricalmetallic tubing from being pulled away from the fitting. However, thehelical or spiral positioning of the gripping tabs permits theelectrical matallic tubing to be removed by simply twisting or turningthe electrical metallic tubing. A contact rib is placed within theconnector body to contact the electrical metallic tubing which improvescontinuity.

Accordingly it is an object of the present invention to provide an easyto use fitting or connector for use with electrical metallic tubing thatcan securely hold the electrical metallic tubing and yet be readilyremovable without disassembling the fitting or cutting the electricalmetallic tubing.

It is another object of the present invention to provide good electricalcontinuity and to provide a relatively low voltage drop across theelectrical fitting, connector, or coupler.

It is an advantage of the present invention that the electrical metallictubing may be simply pushed into the electrical fitting, connector, orcoupler.

It is another advantage of the present invention that the electricalmetallic tubing is securely held and yet is easily removed from theelectrical fitting, connector or coupler when desired.

It is yet another advantage of the present invention that the electricalmetallic tubing fits tightly into the connector body despite variancesin the outside diameter of the electrical metallic tubing.

It is a feature of the present invention that gripping tabs are formedalong a helix or spiral.

It is another feature of the present invention that rounded corners areutilized on the highest and lowest gripping tabs.

It is yet another feature of the present invention that a contact rib isused, improving continuity between the electrical metallic tubing andthe electrical fitting.

These and other objects, advantages, and features will become morereadily apparent in view of the following, more detailed, description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an embodiment of the presentinvention.

FIG. 2 is a perspective view illustrating an embodiment of the presentinvention with an electrical metallic tube placed therein.

FIG. 3 is a cross-section of an embodiment of the present invention.

FIG. 4A is a front elevational view of a gripping or locking deviceutilized in the present invention.

FIG. 4B is a side elevational view illustration the gripping or lockingdevice utilized in the present invention.

FIG. 4C is a perspective view illustrating the gripping or lockingdevice utilized in the present invention.

FIG. 4D is a perspective view taken at a different angle illustratingthe gripping or locking device utilized in the present invention.

FIG. 5 illustrates a coupling embodiment of the present invention forconnecting two tubes together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an embodiment of the present invention assembled. Theelectrical metallic tubing connector 10 has a generally cylindrical body12 having a flange 14 thereon. Adjacent the flange 14 is a threaded end16. The body 12 may be made of a zinc alloy. The gripping or locking end18 contains a gripping or locking device 20. A washer 22 is held withinthe electrical metallic tubing connector 10 by crimped lip 24. Pressedwithin the crimped lip 24 are a plurality of dimples 26 that providepressure to prevent the washer 24 and the gripping or locking device 20from rotating relative to the body 12 of the electrical metallic tubingconnector 10. The washer 22 has a cylindrical aperture or opening 23therein. The diameter of the cylindrical aperture or opening 23 shouldbe substantially the same as that of the outside diameter of theelectrical metallic tubing intended to be connected. The washer 22provides a point of support for the electrical metallic tubing.

FIG. 2 illustrates the electrical metallic tubing connector 10 havingthe electrical metallic tubing 30 inserted therein. Locknut 28 isthreaded on to the threaded end 16. The threaded end 16 is typicallyplaced within an aperture of an electrical box, not shown, with thesides of the electrical box securely held between the locknut 28 and theflange 14.

FIG. 3 is a cross section more clearly illustrating the construction ofthe electrical metallic tubing connector 10 of the present invention.The body 12 has a body bore 32 with a first diameter. The threaded end16 has a threaded end bore 34 with a second diameter. Between the bodybore 32 and the threaded end bore 34 is an intermediate shoulder stop36. Adjacent the intermediate shoulder stop 36 is at least one contactrib 38. The contact rib 38 extends radially into the body bore 32,effectively reducing the diameter of the body bore 32 within the body12. The contact rib 38 extends radially into the body 12 by anincreasing radial dimension while progressing axially or longitudinallyrelative to the body 12. Preferably, there are three contact ribsequally spaced one hundred and twenty degrees apart within the body bore32. Adjacent the body 12 is conical portion 40. Near the large open endof the conical portion 40 is a shoulder 42. The shoulder 42 is adaptedto receive a flat rim 44 of the gripping or locking device 20. Attachedto the flat rim 44 is a tapered angled portion 46 which is attached to aflat ramp 48 on which the gripping tabs 50 are placed. One end of theflat ramp 48 is displaced approximately two degrees (2°) from the planeof the flat rim 44. Accordingly, the flat ramp 48 has a slope or pitchof approximately two degrees (2°). The gripping tangs 50 are equallyspaced and have an equal length but are displaced axially relative tothe longitudinal axis of the body 12 thereby forming a helix or spiral.The equal length of the plurality of griping tangs 50 helps to uniformlyhold the electrical metallic tubing. The gripping tabs 50 flex slightlyand are angled inward away from the circular aperture or opening 23.

FIGS. 4A-D illustrate different views of the gripping or locking device20, more clearly illustrating the positioning of the plurality ofgripping tabs 50. The gripping tabs 50 are positioned or placed in ahelix or spiral and are equally spaced around the inside perimeter ofthe gripping or locking device 20. Accordingly, there is a high endgripping tab 52 and a low end gripping tab 54 that are axially displacedand separated by edge 58. The high end gripping tab 52 and the low endgripping tab 54 have rounded corners 56 that are adjacent or facing eachother. The rounded corners 56 may by shaped or have a metal cutting edgeso as to cut or tap metal. As seen in FIG. 4B the flat ramp 48 isdisplaced by angle 60 form the flat rim 44. Angle 60 is preferably twodegrees. Therefore, the helix or spiral has a pitch of approximately twodegrees. The gripping or locking device 20 is preferably made of aspring metal and may be made of stainless steel, and is harder than thematerial of the electrical metallic tubing.

FIG. 5 illustrates another embodiment of the present invention and is acoupling utilized to connect two sections of electrical metallic tubingor EMT together. The electrical metallic tubing coupler 110 has a body112 adapted to receive a respective end of two sections of electricalmetallic tubing 30. The ends of the electrical metallic tubing 30 arepositioned adjacent intermediate stop 136. Adjacent intermediate stop136 are contact ribs 138. Preferably, there are three contact ribs 138equally spaced one hundred and twenty degrees apart within the bore ofthe body 112. Placed within each end of the electrical metallic tubingcoupler are gripping or locking devices 120 and washers 122. Theconstruction of each end of the electrical metallic tubing coupler isthe same as that described for the electrical metallic tubing connector10 illustrated in FIGS. 1-4D.

The operation and advantages of the present invention can readily beappreciated by referring to FIGS. 1-4D. The electrical metallic tubingconnector or fitting may be pre-assembled and easily attached, in aconventional way, to an electrical box opening by inserting the threadedend 16 into an electrical box opening, not shown, and tightening locknut28. An electrical metallic tubing 30 may then be pushed into thecircular aperture 23 so that the gripping tabs 50 of the gripping orlocking device 20 flex slightly inward, permitting the electricalmetallic tubing to move forward, or inward, contacting the contact rib38 and the intermediate shoulder stop 36. The contact rib 38 permitsimproved electrical contact or continuity between the electricalmetallic tubing 30 and the body 12 of the electrical fitting orconnector 10, thus reducing a voltage drop across the electrical fittingor connector 10. Additionally the contact rib 38 assures that the outerdiameter of the electrical metallic tubing 30 is snugly held within thebody bore 32 and adjacent the intermediate shoulder stop 36 and providesa point of contact assuring no movement or wobble of the electricalmetallic tubing 30 within the body 12. The circular aperture 23 inwasher 22 provides another point of contact for the electrical metallictubing 30 that is spaced from the contact with the contact rib 38. Thesemultiple, separated contact points assure that the electrical metallictubing 30 does not wobble within the electrical metallic tubingconnector or fitting 10. Additionally, the gripping tabs 50 prevent theelectrical metallic tubing 30 from being pulled from or withdrawn fromthe body 12 simply by pulling longitudinally on the electrical metallictubing 30. Therefore, the electrical metallic tubing 30 is securely heldwithin the electrical metallic tubing fitting or connector 10 andprovides a secure connection simply by pushing in the electricalmetallic tubing 30 through the circular aperture 23. Therefore, thepresent invention provides a secure electrical fitting for drylocations, as there are no seals for weatherproofing.

Should it be necessary to disassemble or remove the electrical metallictubing 30 from the electrical metallic tubing fitting or connector 10,this can easily be done without having to cut the electrical metallictubing 30 or disassemble the electrical metallic tubing fitting orconnector 10. Due to the gripping tabs 50 being positioned in a helicalor spiral position, the electrical metallic tubing 30 can easily beremoved simply by rotating the electrical metallic tubing 30, preferablycounter-clockwise, causing it to follow the helical or spiral pattern ofthe gripping tabs, thereby forcing the electrical metallic tubing 30 tobe backed out of the electrical metallic tubing fitting or connector 10.The gripping or locking device 20 is prevented from rotating by thedimples 26 placed in the crimped lip 24 and resulting pressure exertedon the washer 22 and the shoulder 42 of the gripping or locking device20. The rounded corners 56 formed on the high and low end gripping tabs52 and 54 may have a metal cutting edge and aid in cutting or tapping into the electrical metallic tubing 30, essentially cutting or tappingthreads so that the electrical metallic tubing 30 may be reversed out ofthe electrical metallic tubing fitting or connector 10 upon theelectrical metallic tubing being rotated counter-clockwise. Therefore,the electrical metallic tubing 30 can be easily removed from the fittingor connector 10 without disassembling the fitting or connector 10. Theelectrical metallic tubing coupler 110 illustrated in FIG. 5 functionsin an analogues way.

Therefore, the present invention provides a pre-assembled electricalfitting, connector, or coupler that is easily installed on an electricalbox and permits an electrical metallic tubing or EMT to be securelyconnected to the electrical fitting without assembly or tools simply bypushing the end of the EMT into the fitting. The present inventiontherefore saves considerable time in not requiring time consumingassembly of the electrical fitting for each of the numerous electricalconnections often required in construction. Yet should a change ordifferent connection be required or desired the electrical metallictubing can be easily removed from the fitting without cutting the EMT ordisassembling the electrical fitting. This saves considerable time in,and therefore reduces the cost of construction advancing the electricalfitting arts.

While the present invention has been described with respect to severaldifferent embodiments, it will be obvious that various modifications maybe made without departing from the spirit and scope of this invention.

What is claimed is:
 1. An electrical fitting comprising: a body having afirst and second end; a locking end placed in the first end of saidbody; and a plurality of gripping tabs forming a helix held in saidlocking end, whereby a tube can be pushed into said locking end and heldby said plurality of gripping tabs and removed by rotating the tube. 2.An electrical fitting as in claim 1 further comprising: an electricalbox connector formed on the second end, whereby the electrical fittingcan be connected to an electrical box.
 3. An electrical fitting as inclaim 1 further comprising: a second locking end placed in the secondend of said body; and a second plurality of gripping tabs forming ahelix held in said second locking end, whereby two tubes may be coupled.4. An electrical fitting as in claim 2 wherein: said electrical boxconnector comprises a threaded end placed on the second end and alocknut.
 5. An electrical fitting as in claim 1 further comprising: acontact rib formed on said body and extending radially into said body byan increasing radial dimension while progressing axially orlongitudinally relative to said body.
 6. An electrical connector forattaching electrical metallic tubing to an electrical box comprising: abody; a locking end formed on said body; a gripping device comprising aplurality of gripping tabs forming a helix secured to said locking end;a threaded end formed on said body; and a locknut placed on saidthreaded end, whereby an electrical metallic tubing can be pushed intosaid locking end and held by the plurality of gripping tabs and removedby rotating the electrical metallic tubing.
 7. An electrical connectorfor attaching electrical metallic tubing to an electrical box as inclaim 6 further comprising: a contact rib formed on said body andextending radially into said body by an increasing radial dimensionwhile progressing axially or longitudinally relative to said bodytowards said locking end.
 8. An electrical connector for attachingelectrical metallic tubing to an electrical box as in claim 6 wherein:the helix has a pitch of substantially two degrees
 9. An electricalconnector for attaching electrical metallic tubing to an electrical boxas in claim 6 wherein said gripping device comprises: a circular shapedflat rim adapted to be securely held within said locking end; a taperedangled portion formed onto said flat rim; a flat ramp formed onto tosaid tapered angle portion; and wherein the plurality of gripping tabsare formed onto said flat ramp and are angled inward towards said body.10. An electrical connector for attaching electrical metallic tubing toan electrical box as in claim 9 further comprising: a washer having acircular aperture placed adjacent said circular shaped flat rim; a crimpformed on said locking end holding said washer adjacent said circularshaped flat rim and said locking end; and a dimple formed in said crimp,whereby said washer is forced against said circular shaped flat rim andsaid locking end formed on said body preventing relative rotation ofsaid gripping device and said body.
 11. An electrical connector forattaching electrical metallic tubing to an electrical box as in claim 6wherein: one of said plurality of gripping tabs comprises a high endgripping tab having a rounded corner with a cutting edge.
 12. Anelectrical connector for attaching electrical metallic tubingcomprising: a body having a threaded end with a threaded end bore havinga first diameter, a body bore having a second diameter, and a conicalportion forming a locking end; an intermediate shoulder formed betweenthe threaded end bore and the body bore; a plurality of contact ribsformed adjacent said intermediate shoulder and extending longitudinallyinto said body and radially outward by increasing radial amountsprogressing from said intermediate shoulder towards the locking end; ashoulder formed on a large diameter end of the conical portion; grippingdevice comprising a circular shaped flat rim abutting said shoulder, atapered angled portion formed onto the circular shaped flat rim, a flatramp formed onto the tapered angled portion, and a plurality of grippingtabs formed onto the flat ramp and angled inward towards said body; awasher having a circular aperture sized to receive the electricalmetallic tubing placed within the conical portion of said body andadjacent the circular shaped flat rim of said gripping device; a crimpformed around a circumference of the large diameter end of the conicalportion, whereby said crimp holds said gripping device and said washerinto the conical portion of said body; a plurality of dimples pressedinto said crimp forcing said washer and the circular shaped flat rimagainst said shoulder formed on the large diameter end of the conicalportion, whereby said gripping device is prevented from rotatingrelative to said body; and a locknut threaded on the threaded end ofsaid body, whereby the electrical metallic tubing can be pushed intosaid gripping device and held by the plurality of gripping tabs andremoved by rotating the electrical metallic tubing.
 13. An electricalconnector for attaching electrical metallic tubing as in claim 12wherein: the flat ramp forms a pitch of two degrees.
 14. An electricalconnector for attaching electrical metallic tubing as in claim 12wherein: one of the plurality of gripping tabs comprises a high endgripping tab having a rounded corner cutting edge.
 15. An electricalcoupler for coupling two tubes comprising: a body having a first andsecond end; a first gripping device comprising a plurality of grippingtabs forming a helix secured to the first end of said body; and a secondgripping device comprising a plurality of gripping tabs forming a helixsecured to the second end of said body, whereby a respective electricalmetallic tubing can be pushed into said first and second grippingdevices and effectively joined, and removed by rotating the respectiveelectrical metallic tubing.